1. Field of the Invention
This invention relates to a high-speed signal search method, device, and recording medium (which records this method) that searches a signal sequence for the location of a signal that is similar to a pre-recorded signal. This recording medium records a program for executing by computer this high-speed signal search method, and is computer readable. The present invention can be used, for example, for audio signal detection. That is, the present invention relates to signal detection technology which can detect and automatically record the time a specified commercial was broadcast in a broadcast audio signal, and start and stop video recording by detecting a specified theme song.
In addition, the present invention is related to technology that can automatically monitor the timing of applause, the timing of laughter, etc. in a broadcast, and search for a specified scene. Furthermore, the present invention can be applied to the detection of signals in general (video signals, etc.), not just audio signals.
This application is based patent applications filed in Japan (Japanese Patent Application, No. Hei 10-151723, Japanese Patent Application, No. Hei 10-244162, and Japanese Patent Application, No. Hei 11-49184), the contents of which are incorporated herein by reference.
2. Prior Art
A matched filter is a conventional technique of detecting in a signal sequence a region having a desired signal (referred to hereinbelow as a “reference signal”). A matched filter is a technique wherein a correlation between the waveform of the area of the object input signal (referred to hereinbelow as a “window”) and the waveform of a reference signal is calculated as the window moves, and when the correlation value exceeds a fixed value, it is determined that the reference signal is within the window.
However, in this method, there is the problem that because it is necessary to calculate the correlation value while precisely moving the position of the window with respect to the entire area of the input signal, the amount of calculation becomes enormous, and the calculation speed becomes slow.
In contrast, instead of using the correlation value between the input signal waveform and a reference signal waveform, there is also the technique of calculating the feature quantities (that is, a numerical value or a set of numerical values indicating the feature of the signal waveform) of the input signal waveform in this window, and carrying out a comparison between this input signal waveform and the reference signal waveform by using, for example, the correlation value or Euclidean distance between this feature quantity and the feature quantity of a reference signal waveform calculated in advance.
However, in this method as well, there is the problem that it is necessary to calculate the feature quantities while precisely moving the position of the window with respect to the entire area of the input signal, and because it is necessary to compare feature quantities, the amount of calculation becomes enormous, and the speed of calculation is slow.